In this liquid crystal display device, the signal electrodes and the common electrode are alternately located on the same plane, and by applying voltage with respect to the signal electrode and the common electrode, an electric field is generated between the signal electrode and the common electrode and directions of liquid crystal molecules in the liquid crystal layer are controlled by this electric field. A wide viewing angle may be realized by controlling the directions of the liquid crystal molecules by this horizontal electric field.
In addition, high display quality is required in the recent liquid crystal display device, and thus, high luminance is required in addition to the wide viewing angle, in improving the display quality.
As a technology for satisfying both requirements, there is a black matrix on array (hereinafter, called BOA) technology (see Japanese Unexamined Patent Publication JP-A 2006-301505). In the BOA technology, since a light shielding film is disposed on an array substrate where signal electrodes and the like are formed, so as to cover gate wirings, source wirings, and the like, it is not necessary to provide margins on the light shielding film for position shifting at the time of bonding substrates to each other, and accordingly, a width of the light shielding film can be reduced, a high aperture ratio of pixels can be acquired, and high luminance can be realized. In addition, since the light shielding film exists above the array substrate where the electrodes such as the signal electrodes and the common electrode are disposed, the entire electrodes can be covered by the light shielding film in a wide viewing angle range, and accordingly, it is possible to prevent decrease in contrast due to reflection and scattering at the electrode end.
On the other hand, in the liquid crystal display device of a horizontal electric field system, there is a problem that voltage of the signal electrode is easily fluctuated by fluctuation of voltage of the source wiring, through coupling capacity generated between the source wiring and the signal electrode, and this influences the display quality.
In the related arts, in order to solve the above described problem, the influence on the signal electrode due to the fluctuation of the voltage of the source wiring has been suppressed by forming a shield electrode in a region located between the source wiring and the signal electrode. However, since the shield electrode was only disposed in a region adjacent to the light shielding film, there are problems that the light is shielded by the shield electrode, the aperture ratio of the pixels is decreased, and the luminance of the liquid crystal display device may be decreased.
In addition, there is also a liquid crystal display device in which a transparent electrode is disposed over the entire opening portions to obtain a shielding effect (see Japanese Unexamined Patent Publication JP-A 2004-198846). However, in this liquid crystal display device, by disposing the transparent electrode over the entire opening portions, there are problems that transparency of pixels is decreased, the luminance is decreased, vertical components are strongly generated in a line of electric force of the opening portion itself, and the wide range of viewing angle which is a typical feature of the horizontal electric field system is decreased.
The invention has been made to address the aforementioned problems and an object thereof is to suppress the decrease in the luminance due to the shield electrode while suppressing influences on the signal electrode due to the fluctuation of the voltage of the source wiring, in the liquid crystal display device.